If you're familiar with the American Southwest or even if you're a fan of the
paranormal, you've heard of the mysterious stones that move across the surface
of a dry lakebed in Death Valley called Racetrack Playa. Hundreds and hundreds
of rocks, scattered about the surface of this several square mile mudflat,
have left trails behind them where they've moved across the surface. Nobody
has ever seen one move, despite many studies. I came as close as anyone could.

Proposed explanations run the gamut from natural to paranormal to alien. Strange
magnetic forces, psychic energy, alien spacecraft, teenage pranksters, and
even transdimensional vortices have all been proposed. The leading scientific
hypothesis is that the rocks are moved by high winds, on rare occasions when
the playa is wet enough to be extremely slippery, and conditions are just right.
I've always had trouble with this explanation. I used to play in mud flats
as a kid, and when a rock is glued onto that surface it's pretty damn hard
to move. The rocks at Racetrack Playa are quite streamlined, and it's hard
to imagine any wind strong enough to break their bond with the surface and
shove them along deep enough to leave those trails. The real cause of the moving
rocks, it turns out, carries a lot more punch than wind, and requires conditions
that are not oddball and that are easily observable.

In the early spring of 2002, I made one of my many trips to Racetrack Playa
with two friends, Dan Bocek and John Countryman. The surrounding mountains
were still covered with snow, and the playa itself was firm but had a large
lake covering about a fifth of its surface, perhaps an inch or two deep at
its edges, concentrated at the playa's south end where it's lowest. We ventured
out, armed with cameras, shortly before sunrise. The temperature was just above
freezing. The wind, from the south, was quite stiff and very cold. When we
reached the lake, we found to our great surprise that the entire lake was moving
with the wind, at a speed we estimated at about one half of a mile per hour.
The sun was on the lake by now and we could see a few very thin ice sheets
that were now dissolving back into water. This whole procession was washing
past many of the famous rocks. It's easy to imagine that if it were only few
degrees colder when we were there — as it probably had been a couple
of hours earlier — the whole surface would be great sheets of thin ice.
Solid ice, moving with the surface of the lake and with the inertia of a whole
surrounding ice sheet, would have no trouble pushing a rock along the slick
muddy floor. Certainly a lot more horsepower than wind alone, as has been proposed.
The wind was gusty and moved around some, and since the surface is not perfectly
flat and with rocks and various obstructions, the water didn't flow straight;
rather it swapped around as it moved generally forward. Ice sheets driven by
the water would move in the same way, accounting for the turns and curves found
in many of the rock trails.

But don't take my word for any of this. I told you we had cameras, and I captured
the event on video. It's well worth two minutes of your
time:

That nobody has ever seen the rocks move is easy to believe. When there's
water on the surface of the playa, you're not allowed to go out there — and
indeed, you probably wouldn't want to. Thus there's nobody around when the
ice sheets drag the rocks.

We missed the actual event, probably by a couple of weeks, so we didn't get
the first real video of a moving rock. No doubt someone soon will. But we did
see and document all the forces at play, and I think our explanation is far
more plausible than any previous hypotheses.

Update: My hypothesis was finally confirmed in 2014 by a team who beat me to the punch. Read about it here!

Discuss!

1. Measure the size and weight of an "average" Racetrack Playa stone, and measure the depth and width of its track in the dried surface. (a simple track, indicating a smooth-bottommed rock, is preferable)

2. Make a wet clay bed of material equivalent in properties to Racetrack Playa Clay. Adjust parameters and allow tha clay to dry so that it forms polygons similar in size to R-T-P.

3. Place the rock on the clay and measure the force required to move the rock across the dry clay. Apply force in several directions.

4. Carefully add water to the clay, not disturbing the macro surface structure. Again measure the force required to move the rock. Note the depth of the trail.

5. Repeat 4, with increasing depth of water on clay surface. (water will provide some buoyancy for the rock)

6. Consider that the rock becomes frozen in a floating layer of ice. Calculate the force exerted at various wind velocities upon an ice sheet.

7. Consider that additional water may buoy the ice sheet around the rock.

8. Considering the flexibility and deformation of ice, calculate the buoyancy that different ice thicknesses will be able to exert on the rock.

9. If possible experimentally, freeze the rock in different thickneses of ice, and repeat 4 Note the depth of the track. Calculate the depth of the track when the clay dries.

10. Note that the water depth must exceed the height of the sides of the track, or the ice would plane down the track borders.

Rich Persoff, Watsonville, CAJuly 13, 2012 11:11pm

I don't think ice is necessary. It is the effect of the swelling/contraction of the clay, driven by the suns directional warmth or possibly drying of the clay on on side. Study should be easy with a tray of clay from the playa and a heat lamp. None of the stones appear to have moved towards the sun. Shade of the surrounding structures might cause the turns. Put some soil without the clay in front of one of these stones and it will stop.

John Vogler, Oroville, CADecember 5, 2012 8:56pm

Stop making reasons unto why this happened just be hapy there are some paranormal creepy thing in this world :)

Unknown, las cruses, NMDecember 6, 2012 10:29am

Paranormal; things that go bump in the night.

Normal; things that go bump in the night.

Supernatural; I dunno, never heard of it.

If all the arguments for the paranormal were folded and placed in one place, there still would be room for all the tooth picks sold with the packet.

Fun? hell yes. Explicable? ( Macky would concur on usage) yes..

Booh!

Sorry for those with weak constitutions..

Booh!

Did you know people (very recently) that people thought that demons used to visit their beds and take physical delight i their victims?

Sure the evidence was worth speculation. But the derivation to the conclusions was just a bit suspect.

That and Lilith always snores after I visit...If I claimed it was due to my supernatural paranormal prowess or my fertile imagination (a school boy joke?) I would be on conspiracist territory myself.

No, lilith is old and has a fat neck after 5000 years.

Take that Gavin of Cardiff!

Mud, sin city, NSW, OZDecember 14, 2012 2:39am

I think it's easy: swelling / shrinking of the stones makes the moving and the surface (friction) of the stones is rsponsible for the direction.

Kurt Lindlbauer, Buermoos, Salzburg, AustriaFebruary 16, 2013 5:00pm

I can visualise the noted rocks being collared by the ice and held fast, both floating just off the bottom together, as one and being propelled across the lake bottom by strong wind.
bobbing boulders if you will

Baptiste, Newhall, Ca.April 14, 2013 8:55pm

I have, after years of severe studies, finally found a satisfying response. It must be due to some quantum effects. I assume that you all are familiar with the Heisenberg's uncertainty theorem. Given the precisely known position of the stones, their momentum can't be constantly zero. The stones are thus in movement. This phenomenon is, like many quantum effects, not strong enough to explain this macroscopical problem. We therefore have to refere to another phenomenon called superfluids. At very low temperatures (death valley in winter) some fluids (water is a fluid) start to present some strange behaviours (Helium 4 can climb up the sides of a glass and "flow" out of it). The superfluidity of the surrounding mud combined with the before discussed quantum effect is the only reasonable and scientific explanation of the "moving stones of death valley".

I hate doing this cos I usually try my best to be friendly and it will sound aggressive but comments like "Professor" Heinrich's above in particular really grind my gears. As somebody who has studied a lot of quantum theory it is plain and obvious that you have little-to-no understanding of its principles! It seems you've simply whipped out the old pseudoscientific "Appeal to Quantum Physics" fallacy.

Put simply, quantum effects such as Heisenbergs uncertainty principle only apply on atomic scales. This is one of the *most basic* principles of quantum theory. While it is true that each atom in a stone cannot have a momentum of exactly zero (due to the uncertainty principle) their momentums would all be different. Since these differences are, by the very definition of Heisenberg's uncertainty principle, perfectly random they would form a statistical z-distribution centered on zero, causing a net-zero momentum for the stone overall. A net-zero momentum, of course, means there would be no movement.

For somebody claiming to be a professor of physics such a basic lack of understanding of quantum theory is pretty inexcusable. Not to mention that I can't find any mention of your university anywhere in legitimate scientific literature. While I would easily forgive a non-scientist for these misunderstandings a self proclaimed "Prof. Phys." making them is either sorely mistaken or deliberately trying to decieve. Either that or you're just lying about who you are.

Cian, Dublin, IrelandSeptember 15, 2013 5:58pm

A group of scientists recently concluded an experiment on the Playa. Conclusion: the rocks in water but embraced by thin sheets of surface ice, are blown across the Playa by a light but steady wind.

Today's LA Times has a full-page article that starts on its front page about how this is "a mystery no more" - the article implies that people literally had no idea how it happened before these recent tests that the article is about, and even mentions UFOs. If only they were Skeptoid listeners!

Yontef, Los AngelesAugust 28, 2014 2:32pm

Make a comment about this episode of Skeptoid (please try to keep it brief & to the point).